Electric motor driven vehicle and power unit thereof

ABSTRACT

The invention relates to an electric motor driven vehicle having a driving unit assembled with a motor and transmission mechanism. In order to avoid a load in a low rotational state of the motor, the transmission mechanism is connected with the motor and driving wheel within a range of predetermined rotational numbers in which the motor approaches the vicinity of maximum efficiency. Accordingly, motor driving is possible from the start, and because of the small electric power and the low heat generating quantity, cruising distance is extended and the apparatus is consequently made to be compact and of light weight. The transmission is provided with an automatic starting clutch and an automatic transmission, and when a belt type stepless speed change transmission is used as the automatic transmission, operation of the motor near the vicinity of maximum efficiency can always be maintained in the usual speed change range. The driving unit can be constructed compactly as a power unit of swing type. Further, an advantageous cooling mechanism of the motor and a wiring structure of an electric power supply cord are disclosed herein.

This application is a continuation of copending application Ser. No07/552,099, filed on Jul. 13, 1990 U.S. Pat. No. 5,101,924.

BACKGROUND OF THE INVENTION

The present invention relates to an electric motor driven vehicle andthe power unit thereof, and particularly, to an electric motor drivenvehicle and power unit thereof capable of being driven by a motor fromstarting and capable of operation at reduced load at low speed.

An electric motor driven vehicle, such as an electric motor drivenbicycle with a rear wheel driven by a motor through a transmissionmechanism is known, and for instance, is disclosed in Japanese UtilityModel Publication Official Gazette No. Sho-48-14271. In the abovereferenced known electric motor driven bicycle, a chain wound between adriving sprocket and a pedal is capable of being driven by the pedal.The driving sprocket is also made to be possibly driven by a DC motor;the DC motor connected to a battery through a governor. In order tooperate the electric motor driven bicycle, speed is raised by man powerthrough operation of the pedals, and when the speed reaches apredetermined running speed, the governor switch turns ON and the DCmotor is started so that motor driving of the vehicle can be started.

Generally, a motor has a peculiarity that torque and current are largein the case of a low rotational state and efficiency becomes decreased.Here, the efficiency is given by the following expression:

    n=1.027·N·T/(I·V)

(N=number of rotations, T=torque, I=current, and V=voltage).

When a load is applied to the motor in such a low rotational condition,a negative effect occurs in that an amount of electric power consumptionbecomes larger and the cruising distance is shortened. Also, heatgeneration quantity becomes larger whereby deterioration of operationalcapacity soon results. The extent of good operational efficiency of themotor is therefore primarily limited to be within a relatively narrowrange.

Therefore, although it is thought that the motor may not be starteduntil it reaches a predetermined running speed as in the aforementionedexample, it would be advantageous if motor driving and man power drivingcould be applied together in this case. Accordingly, such an electricmotor driven vehicle is expected that can be driven by a motor from thestart.

Further, there is also a need to adopt an integrally structuredtransmission mechanism with the motor to efficiently cool the motorbecause the heat generation quantity of the motor is great. Such acooling system would result in a simplified wiring structure of theelectric power supply cord of the motor.

SUMMARY OF THE INVENTION

Therefore, it is a first object of the present invention to provide anelectric motor driven vehicle capable of being driven by a motor fromthe start and also capable of reducing a load at a low running speedwith respect to the motor.

A second object of the present invention is to provide a power unitemploying the above described driving structure.

A third object of the present invention is to provide an effectivecooling structure in regard to the motor in said power unit.

A fourth object of the present invention is to provide an advantageouswiring structure of the electric power supply cord of the motor.

In order to solve the above described first object, the electric motordriven vehicle of this invention is characterized in that it is anelectric motor driven vehicle which transmits the rotation of a motorthrough a transmission mechanism to a driving wheel, and thistransmission mechanism is connected to the driving wheel only within therange of a predetermined rotational speed approaching maximum efficiencyof said motor.

Further, the approaching of maximum efficiency is establishedvoluntarily while excluding the low efficient range which may becomedisadvantageous by producing either a maximum torque or a large currentin the case when the motor is loaded.

When the rotation of the motor is increased and it reaches apredetermined rotational speed approaching maximum efficiency of themotor, the transmission mechanism is connected to a driving shaft side,and the rotation of the motor side is transmitted to the driving wheelside through the transmission mechanism only within this range.Therefore, motor load at low efficiency is avoided, and since it becomespossible to run the vehicle only within the range of good efficiency ofthe motor, which was relatively limited originally, consumption ofelectric power is reduced. Consequently, the discharging efficiency ofthe battery becomes high whereby battery life is long and the cruisingdistance can be extended And, since the heat generation quantity is alsodecreased, the deterioration of operational capacity can be preventedand durability is therefore increased and, at the same time, since theabove may be implemented with components of small electric power, themotor can be made compact and light.

Further, the transmitting mechanism can be made to be an automaticcentrifugal force clutch or automatic speed change transmission. In thecase of the latter, since the speed change can be carried out in therange of the predetermined rotational speed approaching the maximumefficiency of the motor by the automatic speed change transmission inresponse to the establishment of a speed change condition, the motor isalways kept near maximum efficiency during the speed changing. Further,when the range between two ratios of maximum and minimum efficiency ofthe automatic speed change transmission is established so as to changethe speed while keeping a proper motor rotational speed as it is whenthe motor approaches maximum efficiency in the time of 100% duty factor,the motor can always be operated in a maximum efficiency state withinthe usual speed change range, and thereby the above-described advantagebecomes most remarkably clear. Further, when the duty factor of theusual speed change range is established to be a predetermined value ofless than 100% so the excessive output corresponding to at least anincrement of running resistance being obtained in maximum ratio, theincrement of running resistance can be overcome by the excessive outputeven if the usual speed change range approaches a maximum ratio, andthereby running in maximum ratio can be made more powerful.

For the second object of the present invention, the driving wheel isrotatably mounted to a transmission case movably supported to a vehiclebody, and simultaneously, a belt type stepless speed changetransmission, which is an automatic speed change transmission providedwithin the transmission case connected with this driving wheel, and amotor contained within a motor housing provided to a side of thetransmission case are connected, so that it can be constructed as apower unit for rotationally driving said driving wheel. When the powerunit is made integrally as above, the driving mechanism can be madecompactly.

Further, the entire power unit is contained within the recess formed atthe external surface of the driving wheel, so that it can be madefurther lighter and slimmer, and at the same time, the externalappearance can be made neat and smart. Further, the motor housing andthe transmission case can also be made integrally, in this case, sincethe number of parts can be decreased and simultaneously the stress canbe dispersed to both sides. The strength is thereby improved andsimultaneously, the heat dispersion improves whereby the coolingefficiency of the motor housing side increases. Further, when theelectric power supply cord of the motor is fixed to a cover side mountedfrom sideward of the motor housing, assembly of the motor is madeeasier.

For the third object of the present invention, a port for connecting theinterior of the transmission case and the interior of the motor housingof said power unit is provided, and at the same time, the motor and thebelt type stepless speed change transmission can be cooled by a commoncooling fan. Thus, the entire apparatus can be made compact byimplementing the cooling fan in common.

Further, the cooling fan can also be mounted either to the drivingpulley of the belt type stepless speed change transmission or to therotary shaft of the motor adjoining the port within the motor housing.Even if it is made as such, the entire apparatus can be made compactlyand at the same time, in the case of the latter, the heat within themotor housing can be discharged efficiently to the belt type steplessspeed change transmission side.

Furthermore, it can also be made such that a duct of which one end isconnected with the interior of the motor housing is provided opposite ofthe transmission and another end of this duct is made to be opened tothe interior space of the vehicle, so that cooling air for the forcedair cooling may be fed from this duct to the interior of the motorhousing. If it is made as such, the cooling can be executed byintroducing clean air containing less dust and moisture.

For the fourth object of the present invention, the electric powersupply wire cord of the motor is either arranged in the interior of saidduct, or directly drawn out of the motor housing to its exterior withoutpassing through the transmission case. If it is made as such,interference with the belt type stepless speed change transmission sidecan be avoided, and the wiring becomes easy and at the same time,according to the former, it can be fixed without using any specialcomponent since it is not smeared directly by mud or moisture.

Further scope of applicability of the present invention will becomeapparent from the detailed description given hereinafter. However, itshould be understood that the detailed description and specificexamples, while indicating preferred embodiments of the invention, aregiven by way of illustration only, since various changes andmodifications within the spirit and scope of the invention will becomeapparent to those skilled in the art from this detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from thedetailed description given hereinbelow and the accompanying drawingswhich are given by way of illustration only, and thus are not limitativeof the present invention, and wherein:

FIGS. 1 to 14 show a first embodiment of the present invention, in which

FIG. 1 is a schematic side view of an electric motor driven automaticbicycle;

FIG. 2 is a cross-sectional view taken along line I--I of FIG. 1;

FIG. 3 is a fragmentary diagram of an essential part taken from arrowIII of FIG. 2 which is partly cut out;

FIG. 4 is a cross-sectional view taken along line IV--IV of FIG. 1;

FIGS. 5 and 6 are respectively magnified fragmentary views of anessential part of first and second clutches;

FIG. 7 is a circuit diagram showing a control system of the motor;

FIG. 8 is a longitudinal cross-sectional view of acceleration grip;

FIG. 9 is a cross-sectional view taken along line IX--IX of FIG. 8;

FIG. 10 is a cross-sectional view taken along line X--X of FIG. 8;

FIGS. 11a and 11b are graphs for illustrating a setting method of aspeed change condition;

FIG. 12 is a graph of motor characteristic according to duty factor;

FIG. 13 is a magnified fragmentary sectional view taken along lineXIII--XIII of FIG. 1;

FIGS. 14a and 14b are graphs of a characteristic curve of an electricmotor driven automatic bicycle according to this embodiment;

FIG. 15 is a fragmentary diagram of an essential part according to asecond embodiment which is partly cut out;

FIG. 16 is a fragmentary diagram corresponding to FIG. 2 according to athird embodiment;

FIG. 17 is a graph for a motor characteristic thereof;

FIGS. 18 to 22 are diagrams according to a fourth embodiment, in which

FIG. 18 is a diagram corresponding to FIG. 1;

FIG. 19 is a diagram corresponding to FIG. 2;

FIG. 20 is a magnified fragmentary cross-sectional view taken along lineXX--XX of FIG. 18;

FIG. 21 is a wiring diagram of a battery;

FIG. 22 is a diagram illustrating indicators for indicating remainingquantity;

FIG. 23 is a fragmentary side view of a rear part of the vehicle bodyaccording to the fifth embodiment; and

FIG. 24 is a fragmentary cross-sectional view of an essential part ofFIG. 23.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, the first embodiment of the present invention will bedescribed in detail with reference to FIGS. 1 to 14.

FIG. 1 is a side view of the entire body of an electric motor drivenautomatic bicycle mounted with a power unit according to the presentinvention. The vehicle body frame is structured with front frame 2,central frame 3 and rear frame 4. The exterior side of the vehicle bodyframe is covered by a vehicle body frame made of synthetic resinassembled with leg shield 5, step floor 6, rear cover 7 and under cover8.

Direction steering handle 10 is provided at the top of head pipe 9 fixedto the front frame 2. A front fork 12 for supporting a front wheel 11 isconnected to the bottom end.

The front end of swing type power unit 1 for supporting the rear wheel13 at the rear end is mounted to the rear portion of the central frame 3by a pivot 14 and is supported to be able to oscillate freely upward anddownward. The top surface of the rear portion of the power unit 1 andthe rear frame 4 are connected through a rear cushion 15. A stand 16connected to the central frame 3 covers the bottom surface of the frontportion of the power unit at a storing position not shown, and servesconcurrently as a protection member for the motor, to be describedhereinafter, stored within the interior. A container 19 for receiving ahelmet etc. is provided within the inner side of the rear cover 7between the power unit 1 and the seat 17. This container 19 is formed ofa material for shielding magnetism so that any article such as a floppydisk is not effected by the magnetism generated by the driving motor.

A battery box 20 for storing a battery, such as an electric power supplyfor driving the motor, to be described hereinafter, is provided at theinner side of the under cover 8 in the central frame 3.

A controller 21 for controlling the motor during driving and a charger22 for charging the battery are provided within the inner side of thefront cover 23 at the frontward area of the head pipe 9. Electric wirecord 24 for charging connected to the above noted element is made to beconnectable to an exterior commercially available electric power supplyby opening a lid of the front cover 23, which is not shown.

Further, the controller 21 and the charger 22 can possibly beaccommodated within various places with an integral body or separatebody. For instance, the controller 21 can be provided within the area ofA or B shown by imaginary lines at the rear portion of the vehicle body.The charger 22 can also be provided within the area of C of the vehiclebody rear portion or within the area D of the central portion of thevehicle body. In the case of D position, a lid 25 capable of opening andclosing freely is provided along a portion of the stepping floor 6, andsaid charging cord 24 is made to be capable of being taken out and infrom the lid.

The structure of power unit will next be described with reference toFIG. 2. The power unit 1 is provided with a unit case 26 for supportingthe pivot at the front end. The unit case 26 is an article wherein themotor housing 27 of the front portion, the transmission case 28 of thecentral portion and the gear box 29 of the rear portion are integrallyformed. The motor 30 is contained within the motor housing 27, the belttype stepless speed change transmission 31 within the transmission case28, and the final reducing gear 32 within the gear box 29. The motor 30and the final reducing gear 32 are connected through the belt typestepless speed change transmission 31. The belt type stepless speedchange transmission 31 is an example of a transmission mechanism andautomatic speed change apparatus in this application.

The motor housing 27 is opened to the right side in a direction ofvehicle width, and cylindrical portion 34 of stator housing 33 ofsubstantially cylindrical shape with a bottom is inserted into saidopening portion, which is blocked by the bottom portion 35. The statorhousing 33 is a member for covering the right side opening portion ofthe motor housing 27. A boss 36 protruding inward (central side ofvehicle body, it is the same hereinafter) to its central portion at itsbottom portion 35 and vent 37 of its surroundings are formed andsimultaneously, the external peripheral portion is fixed to the motorhousing 27 by bolt 38. A driver 39 protruding sideward with arectangular tubular shape surrounding the vent 37 is formed outward ofthe bottom portion 35. A driver 39 is, as shown in FIG. 3 as well, amember of substantially hexagonal shape provided with the drivingcircuit, which will be described hereinafter. A plurality of V-shapedcooling fins 40 are provided along the internal surfaces of each latus.Also, FET (field effect transistor) 41, which will be describedhereinafter, is fixed to its external surface.

Further, a cup-shaped cover 42 covering driver 39 is fixed outward ofthe bottom portion 35, and the interior space is made to serve as an airintroducing chamber 43. An end portion of flexible duct 44 is connectedto the cover 42 (FIGS. 1, 2 and 8), and another end portion is coupledto the interior of the container 19 provided at the bottom portion ofthe seat 17. A sponge filter 46 for eliminating the dust within the airis contained within the inlet opening of joint 45 for connecting to duct44 of the container 19 (FIG. 4). The electric power supply wire cord 47for connecting the motor 30 and the driver 39 is led by piercing throughthe interior of the duct 44, which is wired through the cover 42 to theinterior of the air introducing chamber 43 and the motor housing 27.

A partitioning wall 48 is integrally formed to the boundary portion ofthe motor housing and the transmission case 28. Each interior space ofthe motor housing 27 and the transmission case 28 formed by thepartitioning wall 48 are communicated together.

A rotary shaft 50 of the motor 30 is supported by bearings (51 and 52)provided cooperating with the partitioning wall 48 and the boss 36 ofthe stator housing. An end of the rotary shaft 50 is protruded to theinterior of the transmission case 28 by piercing through thepartitioning wall 48.

A rotary shaft portion cooling fan 53 for blowing air through the vent49 at a portion approaching the partitioning wall 48 is providedcooperating with the rotary shaft 50 of the motor 30.

The left side surface of the transmission case 28 is covered by a cover54, and air discharge port 55 is formed at its rear end portion.

The motor 30 is a DC brushless motor, which is provided with a rotor 58arranged with permanent magnet 57 around the external circumference ofiron core 56 fixed to the rotary shaft 50. A stator 62 made of statorcoil 61 is wound around iron core 60 and is fixed to the tubular portionof the stator housing 33 by bolt 59. A magnet 63 fixed to an end portionof the rotary shaft 50 and a rotor position sensor 65 made of three holeelements 64 arranged about the side of boss 36 surrounding this magnetis provided.

For this motor 30, the stator 62 is previously assembled into the statorhousing 33, and then this stator housing 32 is inserted from the openingportion into the interior of the motor housing 27, so that the motorcase is thereby constructed.

The belt type stepless speed change transmission 31 is provided with adriving pulley 66 mounted to the rotary shaft 50 protruding from themotor housing 27 into the interior of transmission case 28. A drivenpulley 68 is mounted to an input shaft of the reducing gear supported atthe rear portion of the transmission case 28. An endless belt 69 iswound between said pulleys 66, 68. The driving pulley 66 consists of afixed face 70 fixed to the rotary shaft 50 and a movable face 71slidably supported in an axial direction to the rotary shaft 50. Acentrifugal force weight 73 movably mounted in a radial direction isarranged between this movable face 71 and a ramp plate 72 fixed to therotary shaft 50. A pulley portion cooling fan 74 is integrally formed onthe side surface of the fixed face 70. The pulley portion cooling fan 74according to this embodiment serves mainly to provide heat discharge inthe vicinity of fixed face 70, and is provided as a subsidiary coolingfan relative to the rotary shaft portion cooling fan 53. Further, thefins may be cut out or made smaller in order to be made lighter, and inthis case, the dimension of the width direction of the cover 54 can bemade smaller.

On the other hand, the driven pulley 68 consists of a fixed face 76supported by a sleeve 75 rotatably inserted relatively around the inputshaft 67 of the reducing gear and a movable face 77 mounted around theinput shaft 67 slidable in an axial direction. The driving powertransmitted to this driven pulley 68 is transmitted to the input shaft67 of the reducing gear through the first centrifugal force clutch 78which is a starting clutch.

The first centrifugal force clutch 78, as shown in FIG. 5, is an exampleof a transmission mechanism and automatic centrifugal force clutch usedin this application. As will be apparent from FIG. 5, it is constructedwith a clutch outer 79 fixed to an end portion of the input shaft 67 ofthe reducing gear, a clutch inner 80 fixed to an end portion of sleeve75, and three arms 81 with each respective first end fixed to the sidesurface of the clutch inner 80 with the respective other ends of each ofthe arms 81 connected by coil springs 82 to each other. Pads 83, capableof coupling with friction to the clutch outer 79, are provided along theexternal peripheral portion. Further, as shown in FIG. 2, spring 84 ismounted between the clutch inner 80 and mobile face 77. The clutch outer79 and the clutch inner 80 are used in combination with the clutch innerand clutch outer of the second centrifugal force clutch 85.

The second centrifugal force clutch 85 operates as an engine brake, aswill be described in detail in FIG. 6, in which respective weight 87 isfixed to the other end side of two bent arms 86 whose respective firstends are mounted to the side surface of the clutch outer 79. Theinterval between both parties are connected by coil springs 88 and pads89, capable of coupling with friction to the clutch inner 80, areprovided thereat.

The first centrifugal force clutch 78 connects the sleeve 75 and theinput shaft 67 of the reducing gear at, for example, over an establishedrotational speed of a little less than the maximum efficiency producingrotational speed of the motor 30. The second centrifugal force clutch 85is established so as to be, for example, about 400 rpm less than theestablished rotational speed of the first centrifugal force clutch 78.

Final reducing gear 32, as shown in FIG. 2, is supported through theball bearings in which the input shaft 67 of the reducing gear andintermediate shaft 90 are respectively provided within the transmissioncase 28 and the reducing gear cover 91. The rotation of the input gear92 of the input shaft 67 of the reducing gear is transmitted through twointermediate gears 93, 94 of the intermediate shaft 90 to an output gear96 of vehicle shaft 95.

FIG. 7 is a circuit diagram showing a control system of the motor, inwhich a potential of potentiometer 101 connected to an acceleration grip100 of the direction steering handle, is used to control the rotationalspeed of the motor 30. A phase signal of the rotor 58 detected by therotor position sensor 65 is inputted to the controller 21, and further,potentiometer 101, switch 102 for detecting a minimum operational angleof the acceleration grip 100, brake switch 103, a vehicle speed sensor99 and driving circuit 104 are connected to the controller 21.

The controller 21 has a microcomputer which determines a duty factor ofcurrent conducted to the motor 30 according to the output signal ofpotentiometer 101 and the vehicle speed sensor, and determines the phaseof an alternating magnetic field in the stator coil 61 according to theoutput signal of the rotor position sensor 65. The controller 21 outputsa PWM signal representing the phase and duty factor for each stator coil61 to a driving circuit 104 and further discriminates the control stateaccording to the output of the switch 102 and the brake switch 103 andoutputs the control command signal to the driving circuit 104 in time ofbraking. The driving circuit 104 includes a gate driving circuit 105 andswitch circuit 106. The gate driving circuit 105 is connected to thecontroller 21, and the switch circuit 106 to the stator coil 61. Theswitch circuit 106 is arranged in such a manner that three pairs of FETs41 wired in series are connected in parallel between a battery 107 andground. The gate of each FET 41 is connected to the gate driving circuit105, and further respective source-drain connection nodes are connectedrespectively with three terminals of the stator coil 61 which isstar-wired. This driving circuit 104 drives the FETs 41 to be ON-OFFaccording to the PWM signal outputted by the controller 21 to therebyconduct the current for generating the alternating magnetic field to thestator coil 61 of the motor 30. The controller 21 conducts signals fromthe terminal to the stator coil 61 by the FET 41 which outputs thecontrol command signal and thereby executes the electrical control ofthe motor 30.

The structure of the potentiometer is shown in FIGS. 8 to 10. Atorsional spring 111 for urging the acceleration grip 100 toward theidling position is mounted between a fixed bracket 109 of ring shapefixed to the middle of the handle pipe 108. A rotary bracket 110 oftubular shape is rotatably inserted to the front end of the handle pipe108, that is, inserted integrally by pressure with the acceleration grip100 to its external circumference. The potentiometer 101 for operatingby rotational operation of the acceleration grip 100 includes a resistor114 and a conductive body 113 printed in parallel on the surface ofarc-shaped printed board 112 fixed to the bottom of the fixed bracket108. Potentials of 0 volt and 5 volts are applied to these conductivebodies 113 and resistor 114, respectively. A guide plate 116 having anarc-shaped guide groove 115 is fixed in parallel with the printed board112 at the interior of the fixed bracket 109. A protrusion 118 formed onthe rear surface of the guide groove 115 of the guide plate 116 is heldto the rotary bracket 110 by passing through the guide groove 115 of theguide plate 116. A metal plate 119 connected electrically to thecontroller 21 is fixed to the front surface of sliding member 117 so asto be contacted simultaneously to the resistor 114 and the conductivebody 113 of the printed board 112. The potential of the metal plate 119becomes about 0.5 volt in the case when the acceleration grip 100 ispositioned at the shown idling position. When the acceleration grip 100is rotated in the shown arrow direction toward the full load position,its potential is increased gradually up to about 4.5 volts in the caseof this embodiment

FIG. 11 is a modeling graph for illustrating a method of establishing aspeed changing condition, wherein a motor characteristic of the motor 30is shown by [I], and a speed change characteristic of the belt typestepless speed change transmission is shown by [II].

Firstly a speed change condition in FIG. 11 will be described. The motorcharacteristic shown by [I] in FIG. 11 corresponds to the case of 100%duty factor, in which this current is shown on the abscissa. Theefficiency, output, rotational speed of the motor and the torque of themotor are shown as ordinates. In consideration of efficiency, asapparent from FIG. 11, a peak of maximum efficiency (η_(max)) isapproximately 90% at about 37.5 A and the rotational speed of the motoris approximately 4500 rpm at this moment.

An efficiency of over 80% is maintained within the range from about 16 Ato 68A, and this range W shown to [II] side) corresponds to a vicinityof maximum efficiency in this embodiment. The rotational number of themotor within this range is about from 3500 to 5800 rpm.

On the other hand, the belt type stepless speed change transmission isestablished with a condition so as to be speed-changed only when it isoperated within the range of over 80% in efficiency which is consideredas within maximum efficiency of the motor. That is, the diagram [II]denotes vehicle speed on the abscissa, and the rotational speed of themotor (and torque of rear wheel driving shaft) as ordinates, andsurrounded by hatched lines, the range of rotational speed of the motorcorresponding to the range of over 80% efficiency is illustrated. Thespeed change curve falls within this range, and the clutch meets at apoint P1 which is a little lower rotational speed than that at

maximum efficiency which produces a rotational speed N_(o) (4500 rpm)obtained with maximum efficiency whereby both the speed and therotational speed of the motor are raised along the low ratio. The speedchange is started with a constant rotational speed from a point P2 ofthe maximum efficiency producing rotational speed, N_(o). This speedchange is increased in speed in a stepless manner by the maximumefficiency producing rotational speed N_(o), per se, whereby executionup to the point P3 crossing with the top ratio. Thereafter, therotational speed of the motor and the vehicle speed are raised togetheralong the top ratio, and then a limiting point P4 of 80% in efficiencyis reached.

The speed at this point P4 is established as a limiting speed (forexample, 60 km/h). When it is done as this, the running of the motor ispossible by maintaining a maximum efficiency (η_(max)) always within theusual speed change range (interval between P2-P3).

Further, although the above described case is an example wherein theduty factor is taken as 100%, in the case when a running resistance isconsidered, as will be described hereinafter, the duty factor within theusual range can be established a little lower.

FIG. 13 shows a supporting structure of the battery box 20, wherein thebattery box 20 is supported on the supporting plate 120 fixed to thecentral frame 3 by protruding toward the right and left directions. Thebattery 107 is contained within its interior to the right and left byinterposing the central frame 3. The battery 107 supplies electric powerto the motor according to the control of the controller 21.

The operation of this embodiment will next be described in detailhereinafter.

This electric motor driven automatic bicycle is constructed in such amanner that the motor 30 is connected with the rear wheel 13 via thebelt type stepless speed change transmission 31, a first centrifugalforce clutch 78, a second centrifugal force clutch 85 and final reducinggear 32. The current of duty factor corresponding to the vehicle speedand the handling angle of the acceleration grip 100 is conducted,whereby running of the vehicle by the driving power of the motor 30 isrealized.

That is, when the motor 30 is started by a start switch which is notshown, the rotary shaft 50 is rotated. In the time when the accelerationgrip 100 is positioned at the idling position and the rotational speedof the motor 30 is small, first and second centrifugal force clutches78, 85 are in a state of cut off, and the driving power of the motor 30is not transmitted to the rear wheel 13 and the belt type stepless speedchange transmission 31 is in an idle running state. Therefore, thecurrent and torque of the motor are not raised over the requirement, andlarge current and high torque produced originally at the time ofstarting and in a low rotational range, as well as the load under thestate of low efficiency, can be avoided. When the acceleration grip 100is rotated from this state whereby the rotational speed of the motor 30is increased, the centrifugal weight 73 is moved axially outwardly alongthe ramp plate 72 fixed to the rotary shaft 50, and thereby the movableface 71 of the driving pulley 66 is moved in the direction approachingthe fixed face 70.

Accordingly, the effective radius of the driving pulley 66 is increasedand at the same time, the movable face 77 of the driven pulley 68 isdriven in a direction away from the fixed face 76 through the endlessbelt 69, whereby the effective radius is decreased. As a result, thereduction ratio of the belt type stepless speed change transmission 31is decreased whereby the rotational speed of the sleeve 75 for rotatingtogether with the driven pulley 68 is increased. Consequently, when therotational speed of the driven pulley 68 reaches the establishedrotational speed in the vicinity of the maximum efficiency producingrotational speed No of the motor, the first centrifugal force clutch 78is connected whereby the driving power of the motor 30 is transmitted tothe input shaft 67 of the reducing gear. The rear wheel 13 is therebydriven through the final reducing gear 32. Thereafter, the motor isspeed-changed in response to the speed change curve shown in FIG. 11 andat this moment, the efficiency of the motor 30 is maintained at thevicinity of maximum efficiency η_(max). Particularly, in the usual speedchange range, it is maintained at approximately maximum efficiencyη_(max) at 100% of the duty factor.

The above is a desirable establishment considering the current custom,wherein the conventional small type scooter is apt to be used in a statethat the throttle is substantially fully opened.

FIG. 14 is a graph showing the running capacity wherein the vehiclespeed is shown as the abscissa, and the rear wheel output and therotational speed of the motor or engine is shown as ordinates. Thecapacities of comparative examples 1 and 2 are noted in combination. Aswill be apparent from this graph, the article of this embodiment, in thecase of comparing with the comparative examples 1 and 2, is obtainedwith lower rotation and higher output. Therefore, the torque and currentrequired to rotate the motor 30 becomes relatively lower while the dutyfactor of the motor 30 becomes relatively less, and thereby, theconsumed quantity of electric power and the quantity of generated heatare suppressed. Since the discharging efficiency of the battery isincreased and is therefore made to have a long life, the motor can beoperated with a correspondingly small current and with resultant lowheat generation quantity, and can therefore be made to be of lightweight and miniaturized. Further, in the usual range, the rotationalspeed of the motor and the rear wheel output can be maintained within anextremely wide range and substantially constant, without the appearanceof a mountain or valley as in the comparative example. Therefore, abroad flat torque characteristic can be realized, and thereby smoothrunning can be obtained.

When the duty factor in the usual range is set, for example, to 60%,excessive output against the running resistance can also be ensured.That is, as the running resistance curve is written in combination inthe diagram [II] of FIG. 11, in the interval between a point P2 to apoint P3, required torque is raised as much as α. Wherein, when each ofthe vehicle speed and the driving shaft torque of points P2 and P3 areset to V2, T2, and V3, T3, respectively, within the interior of the belttype stepless speed change transmission, it happens that the drivingshaft torque at the point P2 is decreased as much as V2/V3 times.Therefore, in order to increase the driving torque and vehicle speed ina direction from the point P2 toward the point P3, the torque increaseof as much as

    T=T3-T2=α+(V3/V2) T2

is required.

However, since the motor characteristic of duty factor corresponding tothe diagram [I] becomes as shown in FIG. 12 when the duty factor of themotor in the usual range is previously set to, for example, 60%, byincreasing the duty factor so as to tie up in turn each peak or theefficiency curve by duty factor from the point P3, the output increasedirected toward the point P4 is ensured, and it is possible to overcomethe increase of the running resistance. That is, the setting of theusual range of the duty factor in the case of 60% enables to ensure 40%as the duty factor of excessive amount against the running resistance,and therefore smoother and more powerful running becomes possible.

Further, the second centrifugal force clutch 85 is connected when therotational speed of the input shaft 67 of the reducing gear reaches overthe established rotational speed less than the established rotationalspeed of the first centrifugal force clutch 78 at a state that power istransmitted from the rear wheel 13 to the belt type stepless speedchange transmission.

Accordingly, during the time of speed reducing or braking, the secondcentrifugal force clutch 85 is connected whereby the torque produced atthe rear wheel 13 is transmitted to the motor 30, therefore, the motor30 can be used as a load. Further, the established rotational number ofthe second centrifugal force clutch 85 is less than the establishedrotational number of the first centrifugal force clutch 78, and sincethe second centrifugal force clutch 85 maintains the connected conditioneven after the first centrifugal force clutch 73 is unengaged in thetime of speed reducing, speed reducing can be smoothly executed wherebya good running feeling can be obtained. Particularly, in thisembodiment, since electric braking is carried out by the motor 30 evenin the time of braking, a better braking characteristic can be obtained.

The cooling system within the power unit 1 will next be described indetail hereinafter. When the rotary shaft portion cooling fan 53provided as cooperating with the rotary shaft 50 is rotated upon drivingof the motor 30, relatively clean air within the container 19 is furthercleaned by passage thereof through the filter 48 provided at the joint45, and is introduced into the interior of the cover 42 through the duct44. This cooling air passes through the midst of the cooling fins 40 ofthe driver 39 contained within the air introducing chamber 43 wherebycooling of the driver 39 which assumes a high temperature by the heatgeneration of the driver and the like. The air that has cooled thedriver. 39 cools the rotor position sensor 65, and then the air flowingfrom the vent 37 of the stator housing 33 into its interior cools thestator coil 61 of the heat-generated motor 30 whereby deterioration ofcapacity according to the heat generation of the motor 30 can beprevented. Thereafter, the air flowing from the vent 49 formed in thepartitioning wall 48 into the interior of the transmission case 28 coolsthe belt type stepless speed change transmission 31 as well as thepulley portion cooling fan 74, and is discharged from the dischargeoutlet 55 to the exterior.

Thus, when the rotary shaft portion cooling fan 53 is positioned nearthe middle of the motor 30 to the belt type stepless speed changetransmission 31 to thereby be implemented in common, the coolingmechanism can be simplified. Since this cooling air can cool the driver39, it is not necessary to provide an exclusive cooling mechanism whichis therefore advantageous. Further, since the rotor position sensor 65which should be kept dust free is provided on the upstream side ofcooling air adhering of dust can be effectively prevented. In this case,since the filter 48 is provided, the air becomes even cleaner. Inaddition, since the inlet of the duct 44 is opened to the space of theinterior of vehicle body, clean air comprising less dust and moisturecan be introduced. Further, according to this embodiment, although theduct 44 is connected to the interior of the container 19, this duct 44can be connected in a suitable manner and place to the frame pipe.

Similarly, since the motor 30 is located upstream of the cooling air,the motor 30 can avoid the heating effect from the belt type steplessspeed change transmission 31 side. At the same time, when the firstcooling fan 53 is made coaxially with the rotary shaft 50, the powerunit 1 can be made to be of small size and light weight. Since thedischarge outlet 55 is provided at the rear end portion of thetransmission case 28, the entire transmission mechanism can be cooled.

Furthermore, this embodiment includes many advantages other than theabove description. Firstly, since the motor housing 27 and thetransmission case 28 are made integrally, the number of parts can bedecreased and at the same time, since the stress can be dispersed toboth sides, strength is increased. Also, heat dispersion improveswhereby the cooling efficiency of the side of the motor housing 27 isincreased.

Moreover, since the stator 62 of the motor 30 can be assembled into theinterior of the motor housing by insertion from into the openingportion, work is easy, and particularly, according to this embodiment,since it is previously fixed to the motor housing 33 and is insertedfrom the opening portion of the motor housing 27, assembling ease isimproved.

Next, since the rotary shaft 50 of the motor serves concurrently as theinput shaft of the belt type stepless speed change transmission 31, anaxial directional dimension of the power unit can be reduced. Further,since the electric power supply wire cord 47 for connecting with themotor 30 and the driver 39 is pierced through the interior of the duct44, mud and moisture and the like splashed onto the duct can be made soas not to directly disturb the electric power supply cord 47 evenwithout using other particular members. Further, when the power supplycord 47 is previously passed through the side of the cover 42, the cover42 can be fixed at the wired state, whereby assembling efficiency isincreased. In this case, it is not necessarily required to pass the cordthrough the cover 42 or its similar functional parts. Since the electricpower supply cord 47 is directly drawn out of the motor housing 27 ofthe opposite side of the belt type stepless speed change transmission tothe exterior, it can be passed to such a place that does not interferewith the belt type stepless speed change transmission 31.

Hereinafter, another embodiment according to the present invention willbe described in detail. With respect to parts common with the previousembodiment, the same reference symbols or numerals are used, and onlydifferent elements will be described in order to avoid furtherexplanation. With respect to the other parts, important matterdesignated with reference symbols and shown in the drawings will beconsidered, and explanation of other elements will be deleted except ina particularly necessary case (hereinafter same).

FIG. 15 is a second embodiment of the first centrifugal force clutch 78and the second centrifugal force clutch 85 provided on the side of thedriving pulley 66, and only the parts corresponding to the belt typestepless speed change transmission 31 of FIG. 2 are shown. In thisembodiment, both clutches are contained about the rear surface of thefixed face 70 of the driving pulley 66. That is, the first centrifugalforce clutch 78 utilizes the fixed face 70 as a clutch outer, and thearm 81 fixed to the base portion side of the fixed face 70 is made to beable to slide with the internal surface of the external circumferentialflange 123 of the clutch inner 122 fixed to the rotary shaft 50. On theother hand, the second centrifugal force clutch 85 utilizes the internalperipheral wall 70a of the fixed face 70 wherein a pad 89 of the bentarm 86 is fixed to the clutch inner 122 extended in parallel with therotary shaft 50 of the motor as a clutch outer and thereby it is madeslidable to this. When it is made as such, the driving pulley 66 can beeffectively utilized allowing a reduction of the number of parts and acompact construction.

Further, both of these clutches can be provided to the movable face 71side of the driving pulley 66, and also can be provided to the movableface 77 of the driven pulley 68 (refer to FIG. 19).

FIGS. 16 and 17 show a third embodiment utilizing a brush type motor.

As shown in FIG. 16, the motor housing 27 is separately constructed fromtransmission case 28, and is fixed by bolt 124. The stator 62 of themotor 30 is fixed to the internal surface of the motor housing 27, andthe commutator 125 is contacted with the brush 127 provided on the sideportion of the motor housing 27 at between the rotor 58 and the wall 126connected to the transmission case 28 of the motor housing 27. Electricpower supply cord 128 of the brush 127 is extended to the exterior ofthe transmission case 28 by piercing through the wall portion of themotor housing 27.

A vent 37 is provided within the cover 129 for covering the right sideopening portion of the motor housing 27, and an air cleaner 130 isprovided to its right side. A suction inlet 131 for communicating theoutside air is formed within the wall surface of the air cleaner 130,and filter element 131 is contained along the inside of this portion.The interior of the air cleaner 130 is communicated with the interior ofthe motor housing 27 through the vent 37. Another vent 49 is alsoprovided within the wall 126, and another vent 49a is formed within theside of the transmission case 28 superposing with the wall 126.

A transmission mechanism according to this application and an automaticcentrifugal force clutch 133, are provided in cooperation with thedriven pulley 68 side of the belt type stepless speed changetransmission 31 connected with the rotary shaft 50 of the motor 30.

According to this embodiment, forced cooling for the parts of the motor30 and the belt type stepless speed change transmission 31 of thetransmission case 28 is simultaneously carried out by the single pulleyportion cooling fan 74. Other parts are generally the same with respectto the first embodiment.

FIG. 17 shows a motor characteristic of this embodiment, the rotationalspeed of the motor is taken as the abscissa, and efficiency, output,current and torque are taken as ordinates. In this embodiment, sincemaximum efficiency η_(max) is obtained in the case when the rotationalspeed of the motor is about 3700 rpm and efficiency is sufficientlyincreased as it is approximately over 50% at 2000-4500 rpm, theefficiency corresponding to this rotational speed is in the vicinity ofmaximum efficiency according to this embodiment. Particularly, accordingto this embodiment, since the duct portion for cooling air can be madeshort and the brush 127 is located at an opposite side of the aircleaner 130 by interposing the motor 30, negative effects on the brush127 caused from dust and moisture sucked in together with air can bedecreased. Furthermore, since the electric power supply cord 128 isdrawn out of a side portion of the motor housing 27 to the exteriorthereof, even though it is made as such, the elements do not interferewith the belt type stepless speed change transmission.

FIGS. 18 to 22 illustrate a fourth embodiment.

FIG. 18 illustrates a side view of the electric motor driven automaticbicycle according to this embodiment, and FIG. 19 shows across-sectional view of said power unit. The front frame 2 and centralframe 3 are channel shaped. The power unit 1 is pivotally fixed to aplate-shaped connecting member 134 extended along to the rearwardportion from the central frame 3, and is contained within recess 135 ofthe convex to vehicle center side formed to the side of rear wheel 13.The motor 30 is arranged so as to be upward of the wheel shaft 95. Acontroller 21 is contained within a small container 19 formed downwardof seat 17.

The interior structure of the power unit has a similar basic structureas the previous embodiment, as shown in FIG. 19, but it is constitutedin such a manner that the air cleaner is deleted. The final reducinggear 32 is simplified and input gear 92 formed in cooperation with theinput shaft 67 of the reducing gear and the output gear 96 on the wheelshaft 95 are directly meshed to each other. Automatic centrifugal forceclutch 133 is arranged near the vehicle body center side to the rearsurface of movable face 77 forming the driven pulley 68. Pulley portioncooling fan 74 is arranged coaxially with the rotary shaft 50 separatelyto the driving pulley 66.

According to this embodiment, since the power unit 1 assembled with themotor 30 is miniaturized to be contained within the recess of the sidesurface of the rear wheel 13, the entire unit is made lighter andslimmer and at the same time, external appearance becomes neat andsmart. Further, since the motor 30 is disposed upward the wheel shaft95, it becomes difficult for mud and water to enter the motor 30.

As shown in FIGS. 18 and 20, battery 107 is contained within the centralframe 3. According to this, assembling and disassembling of the battery107 is easy. Further, the battery 107 is effectively protected by thecentral frame 3. The battery 107 can be implemented in a similar mannerin the front frame 2 side.

Furthermore, the battery 107, according to this embodiment, as shown inFIG. 21, is connected in parallel with the controller 21 and the motor30. The battery 107 itself is structured to utilize a plurality ofindividual batteries 107₁ -107_(N) connected in parallel and theremaining capacity indicator of the battery is implemented by theshifting of switches SW₁ -SW_(N), and lamps L₁ -L_(N).

That is, since constant voltage is maintained when sufficient dischargecapacity is present respectively in each of the individual batteries107₁ -107_(N), each lamp L₁ -L_(N) will be lighted brightly Wherein,when, for example, the switch SW₁ is firstly turned ON and the motor 30is driven, the lamp L₁ is brightly lit in the beginning, but soon thedischarge capacity of the individual battery 107₁ is dropped down by theload of motor 30 whereby the voltage is dropped down.

At this moment, since the internal resistance of the motor 30 is lessthan the lamp L₁, the lamp current is gradually decreased, and the lampL₁ becomes dark. Since this lamp L condition indicates reduction in theremaining discharge capacity of the battery 107₁, a rider may turn ON,for example, the switch SW₂ for switching to the battery 107₂. Thus, inaccordance with the indication based on the lighting condition of alamp, the batteries can be used by switching to one that has a dischargecapacity in turn, one by one, to a next new one.

FIG. 22 is a specific example of a remaining capacity indicator, whichshows a remaining capacity indicator 136 constituted in such a mannerthat the interior of one frame member is partitioned into five sectionsaligned linearly, and five lamps L₁ -L₅ (that is, N=5) are respectivelycontained within a section. The number of indicating lamps isvoluntarily selected.

Thus, when respective lamps L₁ -L₅ are aligned linearly, the number ofbatteries remaining with discharge capacity can be easily accounted foraccording to the number of lamps brightly lit. For example, when all arelit brightly, all of individual batteries 107₁ -107₅ have sufficientdischarge capacity.

In the case when the discharge capacity is 1/2, about half of theindicator lamps (in this embodiment, L₃ -L₅ among the five) are brightlylit. The indicator lamps corresponding to the individual batterieshaving no discharge capacity (L₁ and L₂) are dimly lit. When all areblacked out (or dimly lit), it can be instantly recognized that all thebatteries have no remaining discharge capacity.

Although the usual remaining capacity indication of the batteryconventionally used is indicated by the voltage drop of the battery,since the voltage varies by temperature, there is a case of using atemperature compensation circuit and the like so as to obtain a correctindication. In the case of an alkali battery (Ni--Cd, Ni--Zn) and thelike, since the quantity of voltage drop is small and since such abattery has a characteristic that the voltage does not greatly dropuntil the discharge capacity becomes over 90%, there may be a difficultyin confirming the remaining capacity. In regard to this point, accordingto this embodiment, since the remaining capacity corresponds to thenumber of batteries in use which can easily be recognized, the system issimple in structure and correct remaining capacity indication can beexpected.

FIGS. 23 and 24 illustrate a fifth embodiment wherein the motor and thetransmission mechanism are separately constructed. FIG. 23 shows a sideview of the right side of the rear portion of the vehicle body, whereinthe motor 30 is connected to the bracket 138 provided by protrudingrearwardly the side portion bracket 137 to the rear frame 4. Asupporting plate 140 extending frontward of box 139 meshed with one endof the motor 30 is connected to a bracket 141 extending from the rearframe 4 rearward by bolt 142 to thereby be fixed to the rear frame 4side.

FIG. 24 is a diagram illustrating a transmission mechanism portion bysectional view, wherein rear frame 4 is provided with a pair of memberson the right and left, and both sides of the front end portion of thetransmission case 28 are rotatably supported to each of the rear endportions of supporting arms 144, 145 extended rearward respectively fromthe middle portion of cross pipe 143 connected between said both partiesand the rear frame 4 of the left side. A belt type stepless speed changetransmission 31 similar to the third embodiment, final reducing gear 32and automatic centrifugal force clutch 133 are provided within thetransmission case 28.

Connection of the transmission case 26 and the supporting arm 144 ismade by engaging a boss portion 147 formed to the right side of thetransmission case 28 to a bearing 146 provided cooperating with the rearend portion of supporting arm 144.

Input shaft 150 of the belt type stepless speed change transmission 31is arranged in parallel with cross pipe 143 on a same axis of pivot bolt149. The driving pulley 66 is supported along a first end of the inputshaft 150, and the other end is engaged within the interior of gear box139, to thereby be connected with bevel gear 151. At the same time, theinput shaft 150 is rotatably supported by a ball bearing provided at thewall of the gear box 139 and a boss portion 147 of transmission case 28.Bevel gear 151 is meshed with bevel gear 152 mounted to an end of rotaryshaft 50 of the motor 30.

When the motor is made as such, since the motor side is made to bestationary, and only the side of the transmission case 28 oscillatesaround the input shaft 150 of transmission and pivot bolt 149. Springload quantity is thereby decreased and the oscillating portion can bemade to a required minimum limitation to thereby advantageously improvevehicle lay out. Further, each supporting method with respect to themotor 30 and the rear frame 4 of the transmission case 28 is not limitedto this embodiment but various methods are possible.

Thus, although the embodiments of the present invention are described indetail, the present invention is not limited by the aforementionedrespective embodiments. Without departing from this invention asdescribed in the claims, various changes can be carried out. Forexample, the power unit 1 is not limited to an automatic bicycle but canbe utilized with other vehicles such as an automatic tricycle.

Although the present invention has been described in its preferred form,it should be understood that the preferred embodiments of the presentinvention are not limiting. The scope of the present invention, instead,should be defined solely by the appended claims. Accordingly, changesand modifications in the construction, combination and arrangement ofparts of the preferred embodiments may be contemplated without departingfrom the spirit and scope of the invention defined solely by theappended claims.

We claim:
 1. A drive system for an electric motor driven vehiclecomprising:an electric motor; a driving wheel; a speed changetransmission for transmitting the rotation of said electric motor tosaid driving wheel to run the vehicle, said speed change transmissionmaintaining motor speed within a range preselected to be within adesired percentage of maximum motor efficiency; and an automatic clutch,disposed between said electric motor and said driving wheel, forfunctioning as a starting clutch.
 2. The drive system of claim 1,wherein said speed change transmission varies between two ratios, amaximum ratio and a minimum ratio, which maintains a proper rationalspeed of said electric motor such that said electric motor operates atsubstantially maximum efficiency of a 100% duty factor between said tworatios.
 3. The drive system of claim 1, wherein said speed changetransmission varies between two ratios, a maximum ratio and a minimumratio, and a duty factor during normal transmission is established at apredetermined value less than 100% so as to be obtained within anexcessive output corresponding to at least an incremental amount ofrunning resistance at said maximum ratio.
 4. The drive system of claim1, wherein the drive system is contained entirely in a unitary housingwithin a recess formed on an external side surface of said drivingwheel.
 5. The drive system of claim 1 further comprising:a finalreducing gear operatively coupled between said driving wheel of theelectric motor driven vehicle and said speed change transmission forrotating said driving wheel; and a single unitary housing containingsaid electric motor, said final reducing gear, and said speed changetransmission.
 6. The drive system of claim 5, wherein a rotary shaft ofsaid electric motor drives said speed change transmission, said saidstepless speed change transmission including a driving pulleycomprising:a first movable face slidably supported in an axial directionupon said rotary shaft; a first fixed face formed on an end of saidrotary shaft away from said electric motor; a ramp plate fixed to saidrotary shaft at a position between said electric motor and said firstmovable face; and centrifugal force weight, in slidable contact directlybetween said first movable face and said ramp plate, movable in a radialdirection towards and away from said rotary shaft to vary a distancesaid first movable face is supported along said rotary shaft from saidfirst fixed face to respectively decrease and increase a torque of saidelectric motor.
 7. The drive system of claim 6, said speed changetransmission further comprising:an input shaft, operatively coupled toand rotating said final reducing gear, in response to rotation of saidrotary shaft; a driven pulley comprisinga second movable face slidablysupported in axial direction upon said input shaft, and a second fixedface rotatably supported to said input shaft intermediate said finalreducing gear and said second movable face; and an automatic forceclutch, operating as a braking clutch, operatively connected to saidinput shaft at a first established rotational speed, said automaticclutch coupling a power of said driving pulley to said input shaft at asecond established rotational speed, which is greater than said firstestablished rotational speed.
 8. The drive system of claim 6, said speedchange transmission further comprising:an input shaft operativelycoupled to and rotating said final reducing gear in response to rotationof said rotary shaft; and a driven pulley comprisinga second fixed facerotatably supported to an end of said input shaft away from said finalreducing gear, and a second movable face slidably supported in an axialdirection upon said input intermediate said electric motor and saidsecond fixed face.
 9. The drive system of claim 8, said speed changetransmission further comprising:an automatic force clutch, operating asa braking clutch, operatively coupled to said input shaft and saiddriven pulley at a first established rotational speed, said automaticclutch coupling a power of said driving pulley to said input shaft at asecond established rotational speed, which is greater than said firstestablished rotational speed, said automatic clutch and said automaticforce clutch operatively coupled to said second movable face.
 10. Thedrive system of claim 5, wherein said desired percentage is 80% ofoperational maximum efficiency of said electric motor.
 11. The drivesystem of claim 5, wherein the electric motor driven vehicle is anelectric bicycle.
 12. The drive system of claim 5, wherein said electricmotor operates at 60% duty factor to ensure excessive output againstrunning resistance.
 13. The drive system of claim 1, further including,means for operating said speed change transmission in a high revolutionzone of said electric motor than a peak output revolution of said motor.14. An electric motor driven bicycle comprising:a vehicle body includingfront, central, and rear frame portions extending along a longitudinalaxis of said vehicle body and a drive wheel, having a drive wheel axis,coupled to said rear frame portion substantially planar to saidlongitudinal axis; an electric motor, fixably mounted to said rear frameportion along a first side of said longitudinal axis and coupled to anexternal control means and battery supply, for driving a rotary shaft;and drive means, contained in a single unitary housing pivotallyconnected to said rear frame portion along a second side of saidlongitudinal axis opposite that of said first side and operativelyconnected to said drive wheel, for driving said drive wheel, said drivemeans comprisinga final reducing gear, operatively coupled to said drivewheel, for rotating said drive wheel, and a belt type stepless speedchange transmission, operatively coupling said rotary shaft to saidfinal reducing gear, for rotatably driving said final reducing gear. 15.The electric motor driven bicycle of claim 14, said electric motorfixably mounted to said rear frame portion so as to be mountedstationary above said drive wheel axis.
 16. The electric motor drivenbicycle of claim 14, said electric motor fixably mounted to said rearframe portion so as to be mounted stationary above said drive wheelaxis.
 17. An electric motor driven bicycle comprising:a vehicle bodyincluding front, central, and rear frame portions and a drive wheel,having a drive wheel axis, coupled to said rear frame portion; and adrive system contained in a single unitary housing coupled to saidcentral frame portion by a plate connector, said rear frame portion by aspring member, and said drive wheel, said drive system comprisinganelectric motor, coupled to external control means and battery supply,driving a rotary shaft, a final reducing gear operatively coupled to androtating a drive wheel of the electric motor driven bicycle, and astepless speed change transmission, operatively coupling said rotaryshaft to and driving said final reducing gear, said drive meansimplemented so that said electric motor is positioned above said drivewheel axis, and said battery supply being housed within a batteryhousing space located under a step floor of said central frame portionto lower the center of gravity of the electric motor driven bicycle,said battery supply accessible through said step floor which is a lid ofsaid battery housing space.
 18. The electric motor driven bicycle ofclaim 17, said battery housing space is a box which is coupled to saidcentral frame portion substantially planar to a longitudinal axis ofsaid central frame portion and at a height substantially equal to saiddrive wheel axis.
 19. The electric motor driven bicycle of claim 18,further comprising control means housing under a seat above said rearframe portion.
 20. An electric motor driven bicycle comprising:a vehiclebody including front, central, and rear frame portions and a drivewheel, having a drive wheel axis, coupled to said rear frame portion; adrive system contained in a single unitary housing, coupled to saidcentral frame portion and said drive wheel, comprising an electricmotor, coupled to an external control means and battery supply, drivinga rotary shaft,a final reducing gear operatively coupled to and rotatinga drive wheel of the electric motor driven bicycle, and a belt typestepless speed change transmission, operatively coupling said rotaryshaft to and driving said final reducing gear; and a magneticallyshielded user utilizable vehicle storage compartment.
 21. The electricmotor driven bicycle of claim 20, said magnetically shielded userutilizable vehicle storage compartment is located beneath a seat abovesaid rear frame portion.
 22. The electric motor driven bicycle of claim21, further comprising a battery housing connected to said central frameportion substantially planar to a longitudinal axis of said centralframe portion and at a height substantially equal to said drive wheelaxis.
 23. An electric motor driven bicycle comprising:a vehicle bodyincluding front, central, and rear frame portions extending along alongitudinal axis of said vehicle body and a drive wheel, having a drivewheel axis, coupled to said rear frame portion substantially planar tosaid longitudinal axis; an electric motor, fixably mounted to said rearframe portion along a first side of said longitudinal axis and coupledto an external control means and battery supply, for driving a rotaryshaft; and drive means, contained in a single unitary housing pivotallyconnected to said rear frame portion along a second side of saidlongitudinal axis opposite that of said first side and operativelyconnected to said drive wheel, for driving said drive wheel, said drivemeans comprisinga final reducing gear, operatively coupled to said drivewheel, for rotating said drive wheel, and a stepless speed changetransmission, operatively coupling said rotary shaft to said finalreducing gear, for rotatably driving said final reducing gear, said rearframe being pivotally coupled to said single unitary housing through apair of supporting swing arms along said second side and being coupledto a support plate of said electric motor along said first side, saidpair of supporting swing arms being pivotable along a central axis ofsaid rotary shaft.
 24. A drive system for an electric motor vehiclecomprising:an electric motor; a driving wheel; a speed changetransmission for an electric motor vehicle comprising: an electricmotor; a driving wheel; a speed change transmission for transmitting therotation of said electric motor to said driving wheel to run thevehicle, said speed change transmission maintaining motor speed within arange preselected to be within a desired percentage of maximum motorefficiency; and a centrifugal clutch located between said electric motorand speed change transmission.
 25. The drive system of claim 24, furthercomprising:a transmission, which transmits power of the electric motorto the driving wheel; said centrifugal clutch, directly fixed to saidrotary shaft of the electric motor, being engaged when the rotationalspeed of the electric motor reaches an established rotating speed in thelower speed, thereby transmitting the driving power of the motor to thetransmission.
 26. The drive system of claim 25, wherein saidtransmission is a stepless transmission which reduces the rotationspeed.